The Subcutaneous Implantable Defibrillator

Abstract

This is the fourth decade that the implantable cardioverter-defibrillator (ICD) has been in clinical use for the prevention of sudden cardiac death in high-risk patients.1–5 As initially envisioned, the purpose of the ICD was to prevent death by delivering a direct current shock to the heart within seconds after onset of a sustained ventricular tachycardia or ventricular fibrillation (VT/VF) event. Continuous hardware and software innovations have transformed the identity, meaning, purpose and value of the device.6 Article see p 944 In its first decade of clinical life, the ICD was a minimally featured and, by current standards, bulky device, used exclusively in patients that survived VT/VF, and ≈40 000 devices were implanted yearly in the United States.5,7 Clinical trials of transvenous ICD systems that provided the evidence base to justify the widespread use of the ICD for primary prevention of sudden death in heart failure patients on optimal background neurohormonal blocking drug therapies used devices that had 20 and 30 years of advances.2–5 The ICDs used in the primary prevention trials were able to sense and terminate VT/VF within seconds, defibrillate VF with 70% of ICD recipients.10 Expanded ICD indications and global reimbursement for the device resulted in exponential increases in ICD use, exceeding 350 000 yearly worldwide implants by 2008 and >12 000 devices implanted monthly in the …